Carbon nanotubes (CNTs), comprising multiple concentric shells and termed multi-wall carbon nanotubes (MWNTs), were discovered by Iijima in 1991 [Iijima, Nature 1991, 354, 56-58]. Subsequent to this discovery, single-wall carbon nanotubes (SWNTs), comprising single graphene sheets rolled up on themselves to form cylindrical tubes with nanoscale diameters, were synthesized in an arc-discharge process using carbon electrodes doped with transition metals [Iijima et al., Nature 1993, 363, 603-605; and Bethune et al., Nature 1993, 363, 605-607]. These carbon nanotubes (especially SWNTs) possess unique mechanical, electrical, thermal and optical properties, and such properties make them attractive for a wide variety of applications. See Baughman et al., Science, 2002, 297, 787-792.
The incorporation of CNTs into polymer matrices is currently an area of considerable interest, as CNTs can impart unique properties to the composite or blended material. See, e.g., Mitchell et al., Macromolecules, 2002, 35, 8825-8830; and Zhu et al., Nano. Lett., 2003, 3, 1107-1113. In some cases, CNTs have been covalently integrated into such polymeric hosts.
Another area of interest is CNT-containing fibers. In some reports, such fibers comprise a polymer matrix, whereas in other cases they are largely CNTs. In such later cases, CNT fibers have been spun from CNT suspensions in poly(vinylalcohol) [Vigolo et al., Science, 2000, 290, 1331-1334] and intercalating acids [Zhou et al., J. Appl. Phys., 2004, 95, 649-655; and Ericson et al., Science, 2004, 305, 1447-1450].
In light of the above-described advances in carbon nanotube science, new polymeric systems into which CNTs have been integrated into will continue to expand the range of applications with which they can be associated.